make sure that the shipping server behavior has been changed to use the new shipWeight calculation:
$Shipping_PackageArray[$Shipping_PackageIndex]["PackageWeight"] = "".WA_eCart_FormatNumber($WA_Store_Cart->TotalColumn('shipWeight'), true, 1) ."";
If you still have a problem, make sure the confirm page is properly being uploaded to the server. one way I do this is to add todays date to it inside the body. If I dont see today's date on the page, then I know there is a problem with uploading it.
If your sure it is being uploaded properly and the change in the shipping behavior is made, send a copy of the confirm page so I can take a look.